Energi is the plug-in version of the Fusion Hybrid. It uses the same hardware, a 141-hp, 2.0-liter four-cylinder Atkinson-cycle engine bolted to a front-drive, electronic continuously variable transaxle containing a 118-hp traction motor. Combined system output is identical to the regular hybrid’s at 188 hp, but a larger, 7.6-kWh lithium-ion battery pack that eats up half the Energi’s trunk allows it to operate as an electric vehicle at speeds up to 85 mph.

For people with short commutes or charging stations at work, the plug-in Fusion promises electric-only operation much of the time, while still providing the long-distance range expected from one’s primary vehicle. It’s a compelling pitch, especially given that the Energi is a legitimate five-passenger vehicle with an unassuming countenance, every bit as debonair as the regular Fusion Sedan. The big drawback is, of course, the price. With a base some $11,500 higher than that of a Fusion hybrid, the Energi is expensive, because batteries are expensive. And at $39,495, its sticker price is only $500 less than that of the Chevrolet Volt—not counting the Chevy’s just-anndounced price-drop - which is smaller but has a 38-mile electric range. A $3751 federal tax credit for the Energi shrinks the sticker price some, but Volt buyers for now enjoy a $7500 break, thanks to a battery pack with more than twice the capacity.

When operating in EV mode, the Fusion is down 70 horsepower compared with hybrid mode, but the decrease is masked by the electric motor’s immediately available torque and good accelerator-pedal response, which makes launches from rest feel quick enough. In the city, you’d never suspect the Energi’s 0-to-60-mph time was so slow: all of 14.6 seconds in electric mode. In hybrid mode, that drops to a more normal 8.6 seconds. But at least Ford’s plug-in can do a full-tilt acceleration run without deciding on its own to switch on the internal-combustion engine. Once you’ve selected the EV mode with a button on the center console, the car will heed your command unless you hold the pedal to the floor and keep it there. Even then, you’ll first get a warning query on the gauge display asking you to click “ok” on the steering wheel to start burning hydrocarbons.

We drove our marathon early on a Sunday morning, just like a real one. The first 15.2 miles posed little challenge, at which point we pulled into the public charging station on the University of Michigan’s North Campus with the battery gauge displaying 29 percent. We had covered the fastest part of the course in 32 minutes, and our GPS stopwatch told us we had hit a top speed of 47 mph. We stretched our legs and did some mental math while the car charged and decided we had just under an hour to wait. Ford quotes the Energi’s full recharge time at 2.5 hours on 240 volts and seven hours plugged into a regular wall outlet. We unplugged after 48 minutes, with the dash showing a 66-percent charge and 13 miles of range.

When operating in EV mode, the Fusion is down 70 horsepower compared with hybrid mode, but the decrease is masked by the electric motor’s immediately available torque and good accelerator-pedal response, which makes launches from rest feel quick enough. In the city, you’d never suspect the Energi’s 0-to-60-mph time was so slow: all of 14.6 seconds in electric mode. In hybrid mode, that drops to a more normal 8.6 seconds. But at least Ford’s plug-in can do a full-tilt acceleration run without deciding on its own to switch on the internal-combustion engine. Once you’ve selected the EV mode with a button on the center console, the car will heed your command unless you hold the pedal to the floor and keep it there. Even then, you’ll first get a warning query on the gauge display asking you to click “ok” on the steering wheel to start burning hydrocarbons.

We drove our marathon early on a Sunday morning, just like a real one. The first 15.2 miles posed little challenge, at which point we pulled into the public charging station on the University of Michigan’s North Campus with the battery gauge displaying 29 percent. We had covered the fastest part of the course in 32 minutes, and our GPS stopwatch told us we had hit a top speed of 47 mph. We stretched our legs and did some mental math while the car charged and decided we had just under an hour to wait. Ford quotes the Energi’s full recharge time at 2.5 hours on 240 volts and seven hours plugged into a regular wall outlet. We unplugged after 48 minutes, with the dash showing a 66-percent charge and 13 miles of range.

We soon arrived at the finish line, triumphant, having covered the 26.2-mile course in one hour and fifty-three minutes—and with three miles of range to spare. We’d averaged 28.3 mph during the 55 minutes we were actually driving. Driving home in the aftermath of our world-record-setting marathon, when the Energi seamlessly switched to hybrid operation, we realized we had grown pretty fond of the car.